If you want to drastically improve the efficiency of your pump and reduce maintenance, the first thing to do is change your approach to maintaining your pump. Focus not just on the specialized equipment your plant uses, but on the pipes, valves, and other pieces which are crucial for the plant’s operation.
Did you know that the most common source of wasted energy in pumping systems has to do with seals that weren’t properly sized for their applications? This causes throttling of the pump’s flow, and reduces efficiency. Pumps run in this way also produce higher levels of vibration, which will cause unnecessary damage and reduce the longevity of the seals significantly.
Where does seal failure begin?
While improvements in mechanical seal design have drastically improved their lifespan, using seals outside of their intended environment will cause them to fall short of these estimates. Oftentimes, the problem is that the pump has been used outside of its desired application range. By taking the time to ensure that the entire system is working properly, and fixing problems at their source, you can reach the best efficiency point (BES) and extend the life of your seals.
Root Causes
If a premature mechanical seal failure occurs, there are several common root causes which should be investigated to reach optimal performance for the whole system. In most cases, sealing devices are are being used in an off-design operation. This can cause excess vibrations transmitted throughout the pump, and damages the seals installed in the system.
Avoid these root causes of seal failure
Excessive vibration in the seal chamber cavitation, internal re-circulation, or asymmetrical wear.
Cavitation refers to the vaporization of the fluid and fluid film in the seal chamber.
Temperature increases in the seal chamber under low-flow conditions will cause vaporization of the fluid in the seal chamber.
Insufficient cooling flow from mechanical seal support system.
Critical Seal Components
The mating pair of seal rings is the most sensitive to vibration and insufficient lubrication. Choose these rings carefully based on the conditions of the sealed environment, including the temperature and surface pressures involved. These conditions can change quickly when the seal is exposed to vibration or lacks the sufficient lubrication. Sealing systems try to compensate for changing interface conditions, but off design pump operations may damage the seal if it is forced into a setting it was not intended for. Be wary of more subtle damage which may result from leakage at the seal interface. The cause of this may be unrelated to the material of the seal or its design.
By taking a more involved approach in the subsystems of your pump, you can save money on seal maintenance and improve its overall efficiency. To purchase mechanical seals and other gaskets, visit Real Seal.
There’s no denying that choosing an O-Ring is a daunting decision for newcomers. Just take a look at this website designed to simplify the O-Ring selection. While this website does a great job of compiling O-Ring-related information into a single, easily digestible place, there are simply simply a large number of factors that relate to your O-Ring selection. Understanding the benefits of each material Real Seal provides for your application will make your decision much easier. This blog has already covered silicone more in-depth, so please take a look if you can’t find a material that suits your application here.
EPDM
Ethylene propylene diene monomer rubber, or EPDM, is a versatile material used in a wide variety of applications. It provides excellent resistance to a wide variety of application factors, including: steam, water, heat, ozone, sunlight, mild acidics, alkali, and oxygenated solvents.
EPDM may also be cured with sulphur or peroxide if your application requires it. Real Seal focuses on peroxide-cured EPDM, since peroxide provides better chemical and thermal resistance compared with sulphur. Peroxide-cured EPDM resists up to 150 C (300 F), while sulphur can only resist up to 120 C (250 F). For this reason, peroxide is recommended for applications seeing heavy use.
Peroxide-cured EPDM will improve the heat stability, modulus (elastic stiffness), aging, and compression of the O-Ring. It will be resistant to the following common substances:
Alcohols
Engine coolant
Hot water
Ketones
Organic and inorganic acid
However, it cannot be used with fuels, greases, or mineral oils. If your application involves drinking water, food, or beverages, peroxide-cured EPDM will likely be the best material.
Poyurethane
Polyurethane is a thermoplastic resin which also has elastometric properties. You may recognize polyurethane in various materials around your home. But its unique properties – such as the highest tensile strength and resistance (i.e. to abrasion and tear) of any elastomer – has allowed it to carved out a special niche as an O-Ring or seal as well. Most polyurethanes will work in temperatures ranging from -40 C to 82 C.
Real Seal also offers variant of polyurethane called polyester-polyurethane (AU) and polyether-polyurethane (EU). Within a temperature range of -40 C to 82 C, AU can resist hydrocarbon fuels, oxygen, ozone, and weathering well. AU also features improved abrasion, heat, and oil resistance; however, it deteriorates quickly when exposed to acids, ketones, and chlorinated hydrocarbons.
EU is more resistant to water and humidity than other polyurethanes. Its toughness and abrasion resistance also make it very suitable for hydraulic systems where high pressures, shock loads, wide metal tolerances, and abrasive contamination are involved.
NBR/Nitrile
Acrylonitrile butadiene rubber is also called simply Nitrile or NBR. This elastomer is a great choice for a seal in most hydraulic and pneumatic applications, since it can handle compression set, tear, and abrasion better than most other elastomers. The only downside is that it must be protected from sunlight, though it may resist sunlight better if it is compounded with hydrogenation, carboxylic acid addition, or another substance.
It is used with a wide variety of substances:
Fluids
Fats
Animal and vegetable oils
Flame retardant liquids (HFA, HFB, HFC)
Grease
Water
Air
HNBR
Hydrogenated nitrile rubber, or HNBR, is similar to NBR, but with better resistance to oil and chemicals, and temperatures up to 150 C. NBR, by contrast, may be used between -35 C and 120 C. HNBR is typically used in rubber moulded parts, O-rings, and dynamic seals, as well as high-tensile strength and abrasion applications such as:
Mud motors
Rotary steerable tools
Measurement While Drilling (MWD)
Logging While Drilling (LWD)
FKM
Fluorocarbon rubber is a rubber compound with high chemical resistance, as well as low compression set at elevated temperatures. Though FKM cannot be used with bases, it is compatible with applications involving:
Mineral oils and greases
Aliphatic
Aromatic and chlorinated hydrocarbons
Fuels
Oils
Silicone oils and greases
FFKM
FFKM is essentially FKM with a fully fluorinated polymer backbone that offers superior thermo-chemical resistance. This allows it to be used in most harsh environments, including hot amines, steam, solvents, and hydrocarbons. The downside is that its resistance to lower temperatures is poor.
Aflas/FEPM
Aflas has a chemical structure with excellent heat resistance, chemical resistance, and electrical resistivity. It can also resist chemicals like acids, alkalis, steam, as well as other strong bases (unlike FKM). It does, however, have a weakness to low temperatures in aromatic oils, and poor resistance to mineral oils. It can be used in temperatures from -5 C to 200 C.
No matter what material you need, Real Seal will have the material perfect for your application. Keep checking back here for more information on O-Rings and seals, or contact Real Seal if you have any particular questions.
In a centrifugal pump, a component or cartridge seal may be interchanged, depending on the application. By understanding the advantages and disadvantages of each, you can ensure the optimal performance of your pump.
Component Mechanical Seals
Most standard mechanical seals fall under this category. Replacements of these seals typically include seal faces, holding brackets, O-rings, boots, and parts which must be installed by an experienced pump technician. This is important, as the seal housing’s limited access requires a precise and accurate hand. If just one component is installed incorrectly, the risk of seal failure will increase significantly. There are many components of the seal which need to be installed just right, including seal faces which must be properly seated on the shaft or seal housing, and sliding O-rings and elastomers over shaft shoulders, key ways, and other parts. A mistake installing any of these parts can result in misalignment, damage, and incorrect seal tension.
Cartridge Mechanical Seals
While cartridge seals share many components in common with component seals, there are a few essential differences. Some of the parts come preassembled, like the stationary components which come in a housing; and the rotating components, which come on a shaft-mounted sleeve and are sealed with an O-ring or elastomer. Because of this, installation errors are far less likely.
A key part of successful seal installation is setting the spring tension. Component seals are set manually by adjusting the length of the seal’s spring. Cartridge mechanical seals, on the other hand, have preset spring tensions. A retaining device is used during the installation process to hold the rotating and stationary elements in alignment.
Whether you will be able to install a cartridge mechanical seal will depend on many complex factors affecting the pump. One of the main factors is which side the seal installs from. Most cartridge mechanical seals cannot be installed on the wet side of a pump’s seal chamber, behind the impeller. These seals are generally incompatible with submersible pumps for a similar reason.
Comparing the Two
Deciding between the two seals largely depends on the cost and ease of installation. While the presence of a competent pump technicians might make ease of installation seem like a non-issue, being able to replace a seal during an emergency outage should be a concern.
Unfortunately, cartridge seals cost two to three times more than component seals, so most competitive repair bids you will see often refer to component seals. Although they cost more upfront, in the long-term, cartridge seals are more cost-effective. While component seals require in-service replacement, cartridge seals require less labor costs and less production lost from seal replacement. You’ll also save money on potential errors resulting from potential installation errors of component seals.
In short, mechanical seals are the best choice for users who need a long-term, cost-effective solution for pump maintenance, while component seals are best-suited for users who place a higher priority on a lower upfront cost. For more information or seals and other related components, visit Real Seal.
Are you confident that your system is protected against a seal failure? If not, it could mean a significant setback in production and costs you didn’t have to spend. Protect the investment you invested in by taking these four steps.
1. Choosing the Right Seal
The application, operating conditions, and off-design usage of the seal must be considered carefully before purchase. Even if you simply need a seal to function in hot water, not any seal will do. Boiler feedwater, for example, will not properly lubricate and cool seal faces, resulting in premature seal failure if the wrong seal is installed.
The user must therefore determine that proper operating parameters are maintained. Then, contact must be made with the seal supplier to choose the correct American Petroluem Institute (API) flush plan, seal face combination, and elastomer. It is important to ensure that the proper seal is in place, since every application has its own unique requirements.
2. Proper Installation
Many seal failures could have been prevented simply by a proper installation. Too often, seals are installed without referencing the manufacturer’s instructions, or without taking the proper care to prevent damage on the seal faces or O-rings. Some of the more common issues include: forgetting to tighten set screws before removing setting clips, damaging O-rings, and not tightening gland bolts evenly. Many of these issues can be avoided simply by opting for a cartridge seal over a component seal. The cartridge seal has many of the delicate parts preassembled, reducing the chance for errors significantly.
3. Prevent Excess Heat Generation
Heat generation between seal faces can reduce a seal’s life dramatically by causing problems such as dry-running. The cause is often due to a flooded pump, or an incorrectly vented seal chamber before startup. Another cause might be shaft runout or elevated vibration.
For nearly every application, API 682 will almost always be recommended. No matter if you decide on Plan 11 (a flush line from pump discharge) or Plan 13 (recirculation to pump suction), these systems will keep the seal faces clean, cool, and well-lubricated. Your seal support system will also have an impact on the success of your system. Be sure to discuss these carefully with your seal manufacturer to ensure a cool-running seal.
4. Manage Proper Storage Conditions
Mechanical seals have many unique parts comprised of various materials. If you are not aware of the environments the seals must be stored in, the seals may lose a considerable amount of functionality due to the delicacy of their components.
The seals must be stored in a clean environment, where the temperate and humidity are regulated. If proper care is taken, seals may be stored effectively for up to five years.
Different steps must be taken depending on how long the seals will be stored. A new seal being stored for the next two years should be placed in a clean and cool environment. To prevent face lock and loss of face flatness, rotate the seal faces against each other using the sleeve or shaft two turns every three months, if the seal is not being used.
For new seals being stored for more than two years, or for a seal that has already been in use and will be stored for more than a year, the process is more complicated. Disassemble the seal, clean and dry every component, then store each of its parts individually. O-rings must be in a relaxed state, and placed in their proper environmental conditions, depending on its material. Plug all openings of the seal’s gland in addition to the pump’s seal chamber (if it has not been used). Seal faces should be separated and stored in separate bubble-wrapped packages.
When reassembling the seal after storage, check O-rings for cracks, cuts, and wear. Then, lubricate them to facilitate assembly. Be sure to replace damaged or compression set O-rings. Check the mating ring for cracks or chips, paying special attention to the sealing faces. Contact the vendor for a replacement if damage is found.
To purchase seal components or to learn more about them, please visit Real Seal.
There are many options when it comes to choosing a rubber seal. The profiles can be made of elastomeric compounds through the process of molding or extrusion. The lengths needed for the application are then custom-fabricated from standard rubber products.
There are many different rubber molding processes, including injection, compression, transfer molding, and extrusion. Each process has its own unique advantages, but extrusion is capable of producing complex cross-sections and a smooth surface. These options are available with several different seals, including bulb, bulb trim, lip, door, and accordion seals. There are also extrusions available in solid rubber and sponge rubber, which may then be converted into specialty seals to suit your needs.
There are five different types of extruded seals to consider:
Bulb Seals
Bulb seals have either open, rounded, or teardrop-shaped areas that give them their characteristic look. There are less common shapes as well, such as the crescent and the flat-bottom. Physical dimensions vary, but they usually refer to the height of the inner and outer diameters. Bulb gaskets are typically made of sponge rubber, and are often placed within the door frame of a car or building. Softer bulb seals can be made with EPDM foam in order to create a watertight seal. When used in the automotive industry or construction, bulb seals may be taped instead of mechanically fastened.
Bulb Trim Seals
Bulb trim seals have both a bulb section and a trim section, each with its own durometer. The bulb is usually made from a medium-density sponge rubber such as EPDM. The trim portion is made from materials such as PVC. This unique design allows bulb trim seals to resist water, ozone, sunlight, and temperature extremes. They also come in thermoplastic elastomers, which are weather-resistant, reusable, and recyclable.
Lip Seals
Lip seals have an edge or sealing lip, and sometimes even an opening. Lip seals protect bearings attached to rotating shafts or bores. They retain the lubricant of the bearing, while also preventing dust and other contaminants from entering the seal. One variation on this seal is the radial lip, used in high-speed crankshaft mechanisms found in diesel and gasoline engines.
Lip seals are common in other applications, such as various industrial machines, vehicles, pumps, and mills. If you need this type of seal, choose a material with the right properties for your application.
Door Seals
As their name implies, door seals fill gaps between doors and door frames in order to keep the elements out of vehicles and buildings. Unlike the other extruded seals on this list, door seals are defined by the application they are used in, rather than their shape. Door seals are commonly found in cars and trucks, as well as construction, residential, and industrial facilities. A subset of the door seal known as the hatch seal is used in fuel tanks, electronic enclosures, and rooftop HVAC systems. Certain types of bulb seals also fall under the category of door seals, but these door seals have custom weather stripping as well.
Accordion Seals
Like accordions, accordion seals have folds which allow them to change their dimensions when stretched or compressed. This property makes seals like the accordion boot seal useful in automotive and transportation applications, such as weather-proofing the access points between a truck cab and a trailer. Accordion seals are made from EPDM rubber, and may even contain an internal spring steel loom.
To learn more about the extruded seals available for your application, contact the experts at Real Seal today.
Rubber products, or elastomers, are useful in a wide variety of applications. From industrial seals to medical products, rubber products are an important part of many industries. There are, however, a wide variety of elastomer choices, making it difficult to decide which one is best for your particular application.
One elastomer which many find particularly useful is silicone. Silicone has a number of properties that make it the first choice for many applications.
Temperature Resistance
Silicone is an excellent choice for many applications because it retains elasticity under extreme temperatures. Unlike the material found in rubber bands, silicone does not lose elasticity or become brittle in colder temperatures, and resists damage even at much higher temperatures. Silicone is even used in paint to make the exteriors of houses more resistant to freeze and thaw cycles. Whether the application involves extreme cold, extreme heat, or both, silicone will be an excellent choice.
Flame Retardancy
It takes a lot to make silicone catch fire. This makes it particularly useful in consumer electronics, which need to self-extinguish quickly in case of emergency. For this reason, silicone is used in sealing joint components found in computers and small appliances. It is also commonly found in commercial ovens, food carts, and other industries where higher temperatures are a concern.
Permeability
Silicone’s permeability makes it very useful in applications where the elements are an issue. By using a silicone seal in the door of a car or house, or even the cockpit of an aircraft, silicone will seal out even the most extreme elements.
Durability
Silicone’s durability makes it a common component in the medical industry. Silicone is used as a material for implants because it is accepted by the body, withstands a lot of wear and tear, and allows certain substances to pass through it. These properties also make it useful as a seal covering a wound, protecting it as it heals.
Silicone offers a wide variety of advantages that might make it the best choice for your application. Whether you need gaskets, O-Rings, hoses, door seals, or implants made, silicone is a great choice for many jobs. To learn more about silicone and its applications, contact the experts at Real Seal today.
If you use O-rings in your business, it may be tempting to stock up ahead of time to ensure that your supply is ready when you need it. However, O-rings and other rubber seals are highly sensitive to factors like temperature and humidity, which can severely damage your inventory. Use the following guidelines before re-stocking your O-ring inventory to ensure the maximum ROI:
Packaging
O-Rings must be packaged in a way that protects them from light, ozone, oxygen, and any other contaminants, including dirt. Keep in mind that lubricants and coatings will influence their shelf-life as well.
The bags or boxes that you use are also important: use containers which minimize distortion of the seal (for example, crushing or twisting), as the elastomer will lose performance and shelf-life. For the same reason, avoid overstuffing containers.
Storage Conditions
O-rings must be stored below 100° F (38° C). Like food items, colder temperatures mean better preservation. But before installation, O-rings must be brought back to room temperature to remain flexible. Humidity must be monitored carefully as well, as dry environments will affect the rubber. Too much humidity will cause the seals to absorb water and change dimensions, affecting the performance of the rubber.
Atmospheric ozone can be very destructive for rubber, so be sure to inspect your storage area for ozone-generating equipment that will concentrate ozone near the inventory. Ensure that the room is dark to avoid sunlight and UV light, and be aware of any radiation sources so that you can protect your O-rings accordingly.
Proper Documentation and Stock Rotation
Using the cure date and batch number identification, you should employ the FIFO (“first in, first out”) method of stock rotation. Ensure that your inventory team is prepared to segregate batches, or you may lose important information.
Make sure that you are doing business with an experienced seal distributor will properly label every package in order to maximize O-ring performance and shelf-life. Contact Real Seal today for all of your O-ring questions and needs.
Rubber seals are some of the most versatile products out there, and navigating the vast array of seals available can be daunting on your own. To help you determine which rubber seal is right for your needs, refer to these rubber seal categories conveniently outlined below:
Silicone
Silicone is a material which demonstrates high resilience, temperature stability under extreme heat, and inertness. Silicone comes in several different forms, such as solid, sponge, and foam. Each of these forms has its own special advantages.
Silicone sponge has a closed cell structure, making it ideal for environmental sealing. It can be either soft (2-5 psi) or firm (in the 14-20 psi range).
Like silicone sponge, silicone foam has a closed cell structure and remains stable under UV light.
Other advantageous properties of silicone include being waterproof, flexible (protecting it from damage at extreme temperatures), and shrink-proof.
Neoprene
Neoprene is a type of synthetic rubber made of polymerized chloroprene, which forms a permanent seal. With resilience, tear-strength, and resistance to both UV and ozone damage, neoprene can be a very useful material as long as it avoids petroleum-based fuels. It has excellent resistance to temperatures as low as -40°F and as high as 250°F. Neoprene is also resistant to water and corrosion.
Urethanes
Urethane is a flexible, waterproof, and elastic material that also demonstrates aging and abrasion resistance. It is vulnerable to high temperatures, however. Urethanes come in a variety of blends and formulations.
EPDM
EPDM is a waterproof material with compressibility and aging properties which protect it from UV light, ozone, and oxidation. It comes in varying degrees of density. EPDM combines the closed structure of silicone with the wide temperature resistance of neoprene (from -60°F to 300°F).
This is just a sample of the many materials available at Real Seal. For more industry expertise, contact us today for all of your rubber seal questions and needs.
O-rings and other gaskets are most often used in static seal applications, meaning that the seal is attached and held firmly in place on a gland. Such applications are not damaged by friction or abrasion. If, however, the gland surface moves in relation to the seal, it is a dynamic seal that may require a lubricant to improve performance.
Dynamic applications have two additional factors to consider: break-out friction and running friction. Break-out friction refers to the force that initiates a seal’s movement, while running friction refers to the force needed to keep the seal in motion. Break-out friction can be up to three times greater than the force of running friction.
Choosing the Right Rubber Compound
Some compounds are better suited for dynamic applications than others. While nitrile and EPDM are suitable for dynamic applications, they do tend to have above-average break-out or running friction when used without lubrication.
Silicone and fluorosilicone have poor tensile strength, meaning that they rupture very easily. This makes them a poor choice for high-rate dynamic applications. Reserve these materials for low movement dynamic applications with smooth gland surfaces.
Fluorocarbon is significantly costlier than most other compounds, and cannot be used with steam. It does, however, have better temperature and chemical performance, as well as better running and break-out friction than most other elastomers.
Choosing a Rubber Seal Lubricant
Once you have chosen your material, an OEM engineering team will measure the friction on the seal. This will help you decide whether you need a lubricant to improve the efficiency or longevity of the seal.
External Lubricants
Hydrocarbon lubricants, as well as silicone and barium-based greases, can be applied to lubricants in-stock. These and powder-based lubricants (such as molybdenum disulfide and graphite) are often the best choice for initial reduction of friction. They are compatible with most elastomers and meet high temperature requirements. Additionally, they can provide extra protection from oxygen or ozone damage.
However, there are some negatives to consider as well. If the elastomer and the external lubricant are not chemically compatible, it may cause parts to stick together or otherwise impede assembly operations. Moreover, external lubricants may be lost through dilution into fluids which contact the seal, or through collection away from the seal.
Chlorination
Like external lubricants, chlorination can also be applied to stock O-rings. It is a permanent process which provides a smoother seal surface, reducing running friction. Though it has little effect on break-out friction, it can be used together with an external lubricant to great effect.
Internal Lubricants
Internal lubricants are friction-reducing agents like PTFE, graphite, and molybdenum disulfide, which are mixed into an elastomer. Due to the fact that an internal lubricant is chemically incompatible with the elastomer it is applied to, the elastomer will excrete the lubricant over time. Internal lubricants reduce friction, allow for more consistent performance, and have better assembly productivity in comparison to other lubricants. As with external lubricants, make sure that the internal lubricant is chemically compatible with the fluids it contacts.
Once your elastomer and lubricant are chosen, run the final tests to ensure optimal performance. To learn more or to purchase O-rings and lubricants, contact Real Seal today.
More often than not, the process of parts material selection and/or development can get fairly involved. To sum it all up it a nutshell, it’s similar to a game of pros vs cons where so many different variables come into play. In the case of TPE, the principle is no different. Factors such as meeting the performance requirements for a specific application, economic assessments, and processing issues, should all be reviewed in order to make the optimal choice. Looking at the qualities and considerations of this material can get this quest for the best off to a great start.
What is TPE?
Thermoplastic Elastomers, or TPEs, are flexible materials that exhibit the properties of rubber, but are processed like plastics. Suddenly when they first became available commercially in the 90’s, it was a whole new ballgame for the realm of engineering. TPE’s growth rate escalated as these high-performance materials continued to be used in a plethora of applications. However, just like with other materials, TPE’s scorecard comes with its share of benefits, as well as a few setbacks penciled in.
The Good, the Bad, & the Comparison
Because TPE is processed like plastics, the process is simplified and tends to produce increasing advantages. Due to the need for fewer steps, such as little to no mixing/blending required, TPE can be lead to lower costs and therefore, increased economic advantages. Not to mention, when compared to traditional thermoset rubber, TPE typically also offers:
Shorter fabrication /cycle time
No finishing or post cure required
Lower rate of energy consumption
Recyclable parts, can be used as “filler” in many applications
Lower density that can lead to lower part costs
Although these features can make TPE very beneficial, there are some drawbacks to explore. One being, that the tooling to produce these materials can be expensive, especially if the geometrical design of the part is complex. Also, even though TPE materials over the years, they still haven’t caught up to rubber in terms of their physical properties. When comparing the two, rubber has superior tensile strength, compression set, and elongation capability.
Real Support for Real Solutions
Undoubtedly, there’s plenty of things to consider when selecting a material. But it doesn’t stop there. Even when that’s been covered, other factors exist that can possibly influence processing and impact costs. At Real Seal, we offer engineering and design support to assist customers in their quest for the best and a real solution to their elastomeric product needs. Please contact us if you are interested in support for your engineering application, or call us at 800-542-6162 today.
